Heating system



Wneas:

y, 1936. J. A. SER EL'L 2 047,803

HEATING SYYSTEM Filed April 20, 1929 I 10 Sheets-Sheet l .[we my" Z/b 58 76 M.

J. A. SERRELL.

HEATING SYSTEM July 14, 1936.

10 Sheets-Sheet 4 Filed April 20, 1929 75470 flaf rTeZZ/ WM M fliiorzzqg/s J. A. SERRELL July 14, 1936 HEATING SYSTEM Filed April 20, 1929 10 Sheets-Sheet 5- arm/Pr 6'.

July 14, 1936. J. A. SERRELL 2,047,303

HEATING SYSTEM Filed April 20, 1929 10 sheets-sheet 6 Mair/e56 Jul/6722017 WXQ a I 0 rr July 14, 1936., J. A. SERRELL 2,047,803

' HEATING SYSTEM I Filed April 20, 1929 10 Sheets-Sheet '7 July 14, 1936. J. A s ERRELL 2,047,803

HEATING SYSTEM Filed April 20, 1929 10 Sheets-Sheet 9 July 14,1936. I J. A. SERRELL 2,047,803

I HEATING SYSTEM Filed April 20, 1929 10 Sheets-Sheet 10 Z- k 4% ZZZ/7p i Jeflteb Patented Jul I 1 4, i936 and the like.

UNITED STATES PATENT OFFICE" nnA'rmG SYSTEM John A. Serreil, Pass-A-Grille, Fla., assignor to- Warren Webster & Company, Camden, N. 1., a corporation of New Jersey- Application April 20,1929, Serial No. 356,650

as, Claims.

My invention relates to steam heating systems The general object in a heating system of the character to which my invention relates is to maintain a desired temperature condition in the building to which it is applied.

In the preferred form of the present invention I the heating fluid, which is preferably but not .the

necessarily steam, is applied. tothe radiators or other'heat emitting or'freeing devices in such quantities as will, by relation to the, outside temperature, maintain the temperature within the building at a predetermined temperature or such a schedule of temperatures as may be predetermined.

Any heating. system which is properly designed has the radiators properly proportioned both with respect to the space to be heated and the maximum temperature difierence between the predetermined inside temperature and the outside variable temperature, taking into; account the heating medium which is to beemployed and the range of variation of. a particular variable characteristic the medium which'is' to be governed.

Now, the quantity of heat to be givenlofi from the radiator, assumingfthatroom temperature is kept substantially constant, may be controlled in two general ways, namely, first, by controlling amount 'or per cent ofthe total amount of surface oi the radiator which is heated, that is by variable filling of the radiators with the heating medium or variation oirate of flow of the heating medium deliveredto the radiators, and

'- .second, by varying the temperature of the heating medium within the radiator. Both schemes or varying the heat emission of the radiator may be employed in the same system, and in the prei'erred form of the present invention both such methods are employed in combination.

According to the preferred form of. the present invention, l arbitrarily divide the working range of temperatures, which is assumed in the present case. to be of from negative 10 F. (--10 F.) to 70 E. into predetermined steps or ranges. As will more fully appear, thesesteps may be made as minute as desired, or in fact may, within the' broad method of my invention, be

- considered as a-continuous progression.

Any particular installation will be designed for a given'workin'g range of outside temperature. as,

for example, from 10 below zero F.t 70 F.

Heating fluid which may be suitably controlled is provided to meet the conditions of varying heat requirements. The heating fluid may be steam from-high or low pressure boilers or exhaust -from engines or turbines of power generating systems, or hot water under varying pressure difference or degrees of temperature. Assuming, for example, that saturated steam at pounds gauge pressure is available, this will pr 'de a suitable heating medium ior the operation of my invention;

Now in considering the amount of heat required to maintain a given building or room therein at a predetermined temperature of say 70 F. for. various outside temperatures. lower than 70 F., 10 it'may be considered as accepted that in general the quantity of heat required to maintain such constant inside temperature is directly proportional to the temperature difierence between inside and outside. This disregards varying winds 15 I and radiant heat from the sun which, however, do not change the truth of the fundamental statement. This means that the heat required is a linear function of the outside temperature variation.- It would appear, therefore, to be sim- 20 pie to. provide a direct thermostatic control between outside temperature changes and heat supplied. But there is no simple and direct way to measure or control heat in a heating medium such as steam. '25 Systems are known in which steam is metered by volume throughmetering orifices by the expedient of varying the head of steam impressed upon the orifices, meanwhile keeping the return line at a predetermined pressure, such as atmosall pheric or any selected pressure preferably below atmosphere. This method amounts to partial filling, of the radiators with steam at a certain temperature in accordance with the percent of maximum heat requirement. Such part oi the radiator as-is not filled with steam is filled with air or other non-condensible gases, which may move into or out of the radiator through the open connection with the return main. A practical difficulty is the coordination of volume with controlling temperature diiference, because flow of steam through an orifice. is not a linear function heat emission thereby varied. There are several objections to this system, first, is the fact that the only practicable way of varying steam temperature is by varying pressure. The relation between steam pressure or temperature and heat emission is not a direct linear relation and this introduces a complication.

' Next, with a filled radiator control of heat emission from the radiator is lost. For example, the radiator will waste heat through an open window. A filled radiator will throw off as much heat as its' surrounding medium will absorb. A further difliculty of this form of system as heretofore practiced is the difiiculty of maintaining the high ranges of vacuum, or suction, which systems of this character require to gain the lower steam temperatures desired for mild weather.

Now in accordance with the present invention,

I aim to employ the advantages of metering by a substantially constant differential of pressure between the supply line pressure and return line pressure throughout a part of the range and a varying diiferential throughout another part of l the range, or both variations but in difierent degree in different parts of the working range. of

temperatures.

In the preferred form of the invention, I vary the heat emission of the. radiator through control of the steam temperature by varying the steam pressure in the radiator in one part of the range. In another part of the range I vary the pressure difference between the steam supply line and the return line, to produce a controlled rate of flow which will flll the radiator to a variable degree with steam at return line pressure, the remainder of the radiator being in suchcase dined .with air or other non-condensible gases.

In the preferred embodiment I providea cam or control element. which mechanically embodies the relation between linear temperature variations and non-linear fluid supply or fluid temperature variations, or the like, to giyelinear variation of heat emitted at the radiator in proportion to. the controlling temperature variation. That i is to say, I mechanically compensate for the nonlinear variation of the practical means governing heat delivery so that the resultant heat delivery is actually a linear function of controlling temperature variation. This relation may be embodied in a wide variety of mechanical devices other than a cam which are the equivalent of a cam in my combination for embodying the nonlinear relation. While I speak of mechanical compensation, I intend to include electrical, hydraulic, or similar action.v N k While in the preferred embodiment I show electrical control means for relating the increments or decrements of temperature to the increments or decrements of motion -of the cam or like mechanical device, and show hydraulic means for relating the control exercised by the cam, or the motion of the cam to the pressure or flow regulating valve, I do not intend to be limited to the specific form of the elements but intend that all equivalents are to be considered as-included in the claims hereinafter set forth.-

Also, while I have shown in the preferred embodiment the cam fas governed by relatively coarse increments or decrements of outside temfilled with steam at varying temperatures and the perature, this .is not to be considered as limiting as the motion of the cam may be coordinated to as small increments or decrements of temperature -as may be desired.

In the preferred embodiment, I employ a rotary cam the angular motion of which is proportional to a curve, such as a square root curve or any nonlinear equation, and a cylindrical windlinear equation. Also, as I shall hereinafter show more in detail, I may provide a temperature conwhich are proportional to the square root curve or like non-linear equation. For example, instead of having circuits closed or open upon equal increments or decrements of temperature, the circuits may be opened or closed upon increments or decrements of temperature which are proportional to the square roots oi. temperature.

Likewise, the variable or non-linear relation may be embodied in the contact bank or in any trolled device which acts in steps or increments other link in the chain of elements, if desired, in-

stead of in the thermostat or cam or drum.

Now, in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention, I shall describe in connection with the accompanying drawings a specific embodiment of the same.

In the drawings: Fig. 1 is a diagram more or less conventional 01' a system embodying my invention and having diiferent capabilities. of operation, as will be explained later; a

Figure 2 is a cl uit diagram explaining the electrical connections and the operation of the positional responsive mechanism controlle by the thermostat; i

Figure 3 is a side view with parts broken away of the cam and drum operating mechanism;

Figure 4 is a plan view of the same; Figure 5 is a plan view on an enlarged scale of I the winding drum;

Fig. 5A is an end view of the drum and guide p l y;

Figure 6 is a front eievational view of the selector with its contacts and wipers with parts broken away;

Figure '1 is'a side elevational view 01' the contact mechanism for registering the position of the cam with the thermostat which is active at a particular temperature; Figure 8 is a plan view of the movable contact mechanism;

Figure 9 is a section taken on the line l! of Figure 6;

Figure 10 is a section taken on the line Ill-l0 of Figure 6; f1

Figure his a transverse section through the steam control valve;

Figure 12 is a side view of the sametaken from the right of Figure '11;

Figure 13 is a layout 01' acam;

Figure 14 is a side view of the pressure control .switch contact mechanism;

- Figure 15 is a cross-sectional view of the same on the line l5-l5 of Figure 14;

of pressure control devicei and Figure is a table explaining themagnitude Figure 2; is a detail or the rotatable joint between a swinging pipe and its stationary connection;

Figure 22 is a side view 01' one of the thermostats such as may be employed in accordance with my invention; 7 V

Figure '23 is a vertical section through the same taken on the line 23-23 on Figure 22; Figure 24 is a section taken on the line 24-2 of Figure 23;

Figure 25 is a chart illustrating two modes of varying heat delivery and capable of joint use in my invention;

Figure 26 is a side view of a modified form of thermostatic control element;

Figure '27, which is placed on two sheets and comprising two parts is a diagram of the preierred form 01' my invention; v

Figure 28 is a chart showing the successive steps of supply and return pressure throughout the range of the system;

Figure 29 is a sectional view of a modified tom of the ordinates shown in Figure 28.

Referring, first, to Figure 25, the chart therein shown has abscissae graduated in temperature Fahrenheit. The ordinates are graduated in terms of absolute pressure. This 'chart is not intended to be absolutely accurate but sex planatory only. The ordinates at the right mar-' kin of the chart are degrees of Fahrenheit temperature, of steam corresponding to the absolute pressure at the left. This chart indicates two "separate theories of. steam heating. Curves A and B represent, respectively, supply line pressure and return line pressure in a steam heating system where the variations in heat emission are to-be controlled by varying the temperature of steam within the radiator. some for an outside temperature of zero, steam is supplied at a pressure slightly above atmospheric, that is of the order of 15.7 pounds per square inch at a temperature around 215 and the return line pressure is kept, as by a dlfierentiai control mechanism, at a pressure always below the steam supply pressure by a predetermined amount of the order of l pound-per square inch. Then as the outside temperature rises, by suitable control mechanism the pressure at which steam is supplied to the radiator is reduced successively as indicated by the curve A and thereturn line pressure is maintained a fixed differential below the supply line pressure, as indicated.

by the curve B.

Now, it will be seen that as the absolute pressure is required to be dropped by the curve A the pump which exhausts the return line and causes the reduced pressure in the supply'line' is compelled to do a relatively great amount of work particularly if any leak should occur in the system. The volumes which correspond to the reduced pressure, that is the volume of an expansible fluid such as steam or air which must be handled at the lower pressures is relatively great and at the high vacuum represented by the lower part of the curves A and B the leakage of i 9,047,803 variable hydrostatic column mech-' radiator.

That 15 t0 say.as-:

even a small amount. of air into the system hly detrimental.

A system operating on the fixed difierential principle employs the radiators full of steam and chamber at varies the temperature of the steam by varying the pressure. Such a system as heretofore known and employing steam traps to retain the steam in the radiators has one fundamental defect which for the lower ranges of outside temperature difference is highly undesirable, namely,

' that the emission of heat I om the radiators is not under the control of t e regulating mechanism but under the control or the surrounding medium, that is. the medium surrounding the That is to say, if the occupant of a particular roomwhich is to be kept at a predetermined temperature opens the window of the room, or other opening to the outside, the cold air which is thereby admitted to the radiator is able to abstract heat readily and a very large.

amount of heat may be thrown oil from the radiatorwhich is normally intended to throw off a relatively small amount.

' By such window opening heat may be wasted as the only thing which controls the emission of heat from the radiator'is the temperature difference between the inside of the radiator and the outside, other things remaining the same.

Unless the regulation is held very close to that desired by the occupant of the room, he will open the window to admit fresh air and the radiator tries to heat all outdoors.

Now, referring to curves C and D, the curve D represents a constant pressure which may be any desired pressure. It maybe atmosphere, it

an open atmospheric return is employed, or it may be a pressure b elow atmosphere or it might even be a pressure above atmosphere. As. shown, curve D is a constant pressure which is maintained in the return line and in this case it is .slightly below. 4 pounds absolute pressure. e

C represents the pressure inrthe supply where partial filling of the radiators is employed. Assume that the radiators are of a size that when filled with steam at the maximum pressure and hence temperature for the coldest outside temperatures for which the system is designed they will keep the inside of the building at asuitable temperature such as F. "Between the supply main and the interior of the radiator a metering orifice is employed and this metering orifice restricts the fiow of steam, but

under variations of pressure delivers'variable flow in accordance with known-laws of flowthrough an orifice. v will keep the radiator fractionally filled with a correspondingly variable volume of steam, the

remaining volume of the radiator-which is not filled with steam being filled .with non-condensible gases which are free to flow into or out of the radiator through -the open connection'between the radiator and the return main.

Such; variable rate of fiow' Assuming that at zero temperature, for which.

chart Figure 25 has been drawn as the maximum temperature diflerence between inside and outside, the radiator is filled completely, then for each successive outside temperature represented by the chart the radiator will be partially filled with steam, the percentage of fillingwith' steam corresponding to the percentage of maximum temperature difference represented by the particular prevailing outside temperature. In each case the part of the radiator'not filled with steamcontains air or other gases. Thus, for example, at zero the maximum diilerence between inside temperature and outside prevailing temperature exists. The radiator is, therefore, 100% full of steam. At the other end of the curve when the outside temperature is 70, and assume that the 5 inside predetermined temperature is 70, no temperature difference exists, that is, the difference is zero, and hence zero percentage of the radiator is to be filled with steam, or in other words the entire space within the radiator is occupied by air or other gases.

Now, the temperature of the steam in the radiator is substantially uniform as represented by the line or curve D, since that is the pressure prevailing in the return line and in the radiator, the radiator outlet being open to the return line. With the scheme of heating represented by the curve AB as heretofore known filled radiators throughout are essential and a thermostatically or other suitably controlled steam trap to prevent the escape of steam out of the radiator into the return line is essential.

In the'partial filling scheme represented by the curve C--D the radiator is never filled except at maximum load and steam traps are not required although as a practical convenience they may be and are sometimes employed. Now I'wish to point to the fact that the system shown in Figure 1 is capable of operating a steam heating system on either one of the aforesaid theories. That is to say, with the mechanism of the diagram shown in Figure 1 I may operate on the constant differential principle represented by curves A and B, or I may operate on the partial filling theory of curves C and D and automatically, in accordance with outside temperatures, maintain the temperaturewithin the building, or structure to be heated, at the predetermined value. That is to say, Figure 1 shows'a system of automatic regulation which is operable either 40 in accordance with the constant differential, constantly filled radiator theory or in accordance with the variable diflerential partially filled radiator theory,

Next, I wish to point out that neither system of heating as above described is completely free of defect and that in accordance with one phase of my present invention I may combine the two theories to secure a highly advantageous result.

. 'I'hat is, according to one form of my invention, I propose to employ partial filling of the radiator with steam during the time that there is small heat requirement, that is in the part of the range of operation in which thedifference between the outside prevailing temperature and the predetermined inside temperature is relatively small and the requirement for heat emission by the radiator is, likewise, small, and to employ in the ranges of temperature where the difference between the outside prevailing tems0 perature and the inside pgedeterminedtemperature is relatively high to usethe filled radiator and to vary the heat emitting qualities of the the heat emission of the same according to the Part of the curves A and B lying to the left of the points I: and F in Figure 25, and assume that 75 for temperatures higher than 25 1'. partial filling of the radiator is employed with the steam in the radiator at a flxedor substantially fixed temperature, the system would then operate accord- 5 ing to that part of the curves C and D lying to the right of points E and F. 5

' It is to be observed that the difficulty of a constant differential system as represented by the curves A and B resides in, first, the difficulty of maintaining the highvacua for low heating rate and, next, the possibility of heat wastage as by 0 open windows and the like.

If the system were operated according to the curves 0 and D, it will be seen at once that a radiator of larger volume would berequired to provide the fractional relation below the maxi- 15 mum represented by the rate of flow due to the pressure difference represented by the length of the line between the points G and H on Figure 25.

By employing a radiator of acapacity no larger than the rate of flow due to the pressure difference that is. represented by the length of the line between the pointsE and F all the advantage of the lower temperature difierencerange lying to the right of the points E--F may be secured and all the advantage ofaihe constant differen- 25 tial filled radiator system lying to the left of the points E-F on lines A and B may be employed.

, That is to say, according to this mode of operasure, it is to be understood that the absolute pressure of the line D which is the base line of the vacuum return system may be any desired value without departing from my invention. It is,

however, desirable to operate at a pressure less than atmospheric in order to have steam temperatures which are relatively low and, therefore, suitable for the low rates of heat emission represented by relatively high outside temperatures.

Now referring to Figure 1, I show a steam supply main I connected through a control valve 1 to a distributing main 3 which in reality is the supply main for the radiators 4, 4. While, only two radiators are shown as connected to the branch pipe 5 from the supply main 3, it is to be 55 understood that any number of branches and any number of radiators within the capacity of the system is contemplated. 'I'he radiators 4, 4 and the like have control orifices 6 interposed between the branch pipe which supplies steam to the radiators and the inside of such radiators. These'oriflce plates 6, 6 may be inserted in any suitable manner and may be changeable in order to modulate'the rate of delivery, but upon being adjusted, are functionally fixed. The radiators, such as-4, 4, are provided with steam traps I which may be of the well known thermostatic type operating to close the outlet from the radiators to the return main 8 when steam impinges upon them and tends to pass through outlet opening of the radiator to the return line I. The construction of such themestatic traps is well known. i-

. The returnline 8 leads back to a suitable suc- ,tion pump II which may be driven as by a motor-.75

main 3 is under the control of the valve 2 which is remote controlled, that is it is motor operated as, ,ior example, by a pair of motors such as H and I2 operating on a common shaft l3 having a worm l4 connected to a worm gear |5 for driving a threaded nut upon a stem It for moving a valve plug or controlling member ll. (see Figure l1) towards or away from a seat, such as |8.

The detailed construction of the valve 2 is shown in Figures 11 and 12. The motors II and l5 l2 are connected to a common worm shaft I3 having-the worm |4 cooperating with a worm wheel I 5 which drives the pinion shaft l9.

The pinion shaft l9 has a pinion 2|) meshing with the gear 2| and the gear 2| has a threaded hub 22 forming a nutfor operating upon the threads of the valve stem 5. Thus byrotation of the motor shaft in one direction the stem I6 will be moved endwise in a corresponding direction and when the motor shaft is reversed, the

stem it will travel in the reverse direction. The

valve plug member IT is given a suitable shape which will, for equal increments of axial motion of the stem |6, provide equal increment of flow.

A guiding stem 24-is guided in a tubular extension The control of the motors II and I2 is exere cised by a suitable pressure diflference measuring instrument 38 which I term a pressurestat. The

pressurestat 38 is a zero method pressure dif-' ference control device, that is to say, pressures upon opposite sides of the flexible diaphragm 3| are normally balanced and the circuit through the circuit controller 32 is normally open. when the flexible member 3| moves in one direction from zero because of the difference .in pressure upon opposite sides, one of the circuit wires 33, 34 will be closed to actuate one of the motors H for moving the valve plug |I.

The pressurestatcomprises the flexible metallicbellows member 3| of inverted cup shape having a bottom or plate member 35 connected through a suitable stem 35 to a system of levers 31 which multiply the motion of said plate 35 "and transmit the same 'to the circuit controller 32. The circuit controller is shown more in detail in Figures 14 to 16, inclusive. It comprises a rocking shaft 39 having an operating arm 48 and a link 4| which link is connected to the lever system 31 so that motion of the levers of the system 31 will tend to rock the shaft .39 in one direction. or the other. The shaft 39 has mounted thereupon the spring clips 42 and 43 and these spring clips support mercury bulb switch members 44 and 45. The mercury bulb 44 has a body of mercury therein into which the terminal. -.7o 45 dips at all times, and when the shaft 39 is in neutral position, thecooperating contact member 41 lies just out of contact with the body of mercury in the bulb 44. The bulb 45 likewise contains a body of mercury and a contact 48 which dips into-the mercury and a contact 49 at effect uponthe level in the fixed accumulator 51.

the opposite end which-lies just above the level of the mercury. The contacts 46and 48 of the two bulbs are connected to the common wire 50 and the contacts 41 an 49 are connected to the wires 34 and 33, respe tively, and these wires 5 when the shaft 39 is inneutral position'are both open.

Now it can be seen that if the shaft 39 is rocked in either direction, circuit through one of the wires 33, 34 will be closed to a correspondo ing motor of the pair |2 so as to operate the valve plug in the desired direction. Opening or closing of the valve plug alters thepressure prevailing'in the supply pipe 3 to the radiators 4, 4 with the resultthat a tendency is set into 15 operation which will restore the pressure balance in the pressurestat 38. The diaphragm member 3| is contained in a housing 5| having a removable cover 52 to permit access to the control switch 32, if need for the same should arise. The 20. diaphragm plate 35 is restrained between two limiting plates 53 and. 54 forming part of the pressure chambers on opposite sides of the diaphragm member 311. The chamber below the diphragm member 3| is defined by chamber 25 member 55 which has flanges cooperating with the flanges of the main chamber member 5| and adaptedto secure the margins of the corrugated diaphragm 3| between the flanges so as to make a; tight joint. A pipe 56 communicates with the 30 bottom chamber, that is below the flexible diaphragm 3|; this pipe 58 leading to a constant level chamber 511. This constant level chamber is termed a fixed accumulator and it contains a body r condensate, that is water condensed from 35 the steam supplied by the supply pipe 3, and the level in said chamber 51 is maintained by an.

overflow connection 58 which leads through the water draining trap 59 to the return system or flexible diaphragm 3| so that a change in position 4 of said flexible diaphragm will have very. little The top of the flxed accumulator communicates by way of pipe 6| with the supply pipe 3 so that which is'normally filled with an insulating oil 5;

so as to-preserve the'insulationof the electrical controller 32 which controller is contained in the hpusing 5|. An oil reservoir 82 is provided for maintaining said upper chamber in the housing 5| full of insulating oil and a drain valve 63 0- a is provided for draining the oil out of said chamber in the housing 5| when it is desired toopen the housing to inspect or repair the controller 32. .The bottom of the oil reservoir 62 is connected to a flexible pipe 84 and also has an inlet 5 control'valve 65 for the constant inilow of a small amount of liquid. such as water, to maintain the flexible pipe 64 full of liquid and to maintain the level of liquid in the chamber 66 even with the top of the overflow connection 61. 70 The chamber with its connections I term the variable accumulator I8. The overflow connection 61 of the variable accumulator 10 comprises a flexible pipe which is adapted to be coiled upon a suitable support'll. m I

The support H may be a conical member upon 'which the flexible pipe 68 is adapted to coil itself in a predetermined form, preferably so as to maintain a constant drainage through said flex: ible pi e, either to atmosphere or to the return main 8, as the case may be, a suitable two-way valve 12 being provided for connecting said pipe 88 to either the return main 8 or to atmosphere.

Now considering so much or the system as has been described and assuming that the level 01':

liquid in the chamber 66 is the same level as the level of the surface of the liquid in fixed accumulater 51, and assuming that valve i2 is open to the atmosphere, under these conditions the pressurestat is in neutral position and ii the pressure of steam withln the supply pipe 3 is atmospheric, the pressurestat remains in equilibrium. Likewise, assume that the return line 8 is open to atmosphere, as through the branch i5, and the valve 'HLwhich' is open, so that atmospheric pressure prevails within the radiators i, 4. The traps 1, if they are not open, will tion to force the diaphragm plate 85 upwardly and close the circuit for motor i2 which tends to open the valve 2.

Opening of the valve will proceed until a pressure is established in the supply line 3 which acting through the pipe 8| upon the surface of liquid in the fixed accumulator 81 will bring the pressurestat to balance and open the circuit oi motor [2, the circuit of motor H remaining open. Thereupon a certain pressure difference between the supply main and the interior of the radiators is imposed upon the orifices 8 and a flow'through such orifices occurs partially filling the radiators with steam. The percentage, of filling oi the radiators 4, 4 with steam then corresponds to the percentage oi. the total range of operations represented by the difference between graduations 60 and 10. In other words, if the dinerence between 60 and 10 represents 10% of the range, then 10% oi the radiator will be filled. The condensate of the radiators then is returned through the return pipe 8 and is drained to atmosphere as through the branch 15. II the pressu'restat I0 is now raised to a higher value, as, for example, to the graduation 50, a vfurther increase in the pressure in the supply pipe 8 will be occasioned. Thus throughout the entire range of outside temperatures for which the system has been designed, the proper supply of steam to secure corresponding partial filling of the radiators l, 4 may be secured by manually adjusting the height or the accumulator 18 to the corresponding scale graduation.

It instead oi operating with the base line, that is the return pipe pressure, at atmospheric it is desired to operate at a sub-atmospheric pressure, p then the atmospheric branch 18 may be closed stantially fixed. value of subatmospheric prestion to, there will be a preponderance of prespump Ill will first evacuate the return line and the radiators and will reduce the pressure'prevailing in the supply pipe 3 and its connected branches. The controller 80.when it has reduced the pressure to a fixed value for which the controller is set, will stopthe pump and hold the vacuum on the system. The pressure upon opposite sides of the pressurestat 30 is balanced at this time, assuming that the valve 2 is closed, and h nce the controller 32 is opened, that is v in neut a1 position, and the valve 2 will not be opened. However, if the variable accumulator "m be now raised, for example, to the graduasure upon the top of the diaphragm 8! resulting 20 in operation of the controller 32 to energize the motor 62 and to open the valve 2 until the pressures upon opposite sides of thediaphragm M are equalized, whereupon a corresponding steam pressure will exist in the supply pipe 3 above the base or, reference pressure in the return line 8.

Thus by manual adjustment of the variable accumulator ill to the various points throughout the range of operation the heat emission of the 30 radlatorsmay be controlled in accordance with the requirements determined by outside temperature. 1 Under this scheme of partial filling oi the radiators which corresponds to the curve C-D 35 of Figure 25 the heating fluid is metered out to the radiators and the rate of heat emission is not subject to variation inasmuch as the rate of flow to the radiator is controlled and no more heat can be emitted than the rate of fiow oi fluid will yield. For this mode of operation at either atmospheric return line pressure or sub-atmospheric return line pressure the traps l are not essential but may be employed to'prevent the escape of steam in case theproportioning oi the radiators to the steam flow is not strictly accu-. rate. When the variable accumulator 70 has been raised to the zero mark onethe scale 78 corresponding to maximum output of heat the radiators 4, 4 are to be completely filled without r closing the steam traps.

The system thus far described may also be. operated on a constant differential with variable steam pressures and temperatures according to the curves A-B on Figure 25 by maintaining a constant pressure difference between the supply and the return line as by means of the diiierential regulator 88 which is subjected to the two pressures, namely, the supply line pressure through the pipe 84 which'communicates with the supply pipe 8, and the connection 88 which communicates with the return line pressure.

The pressune regulator 88 comprises two expansible elements of different ei'teetive diameters 88 and 81 which will balance and open the motor circuit only when a predetermined diflerence in pressure between the supply line and the return line is maintained. It is to be understood in practice that condensers with constant levels such as that shown at 51 may be interposed. in the pipes 84 and 85 to prevent accumulation of condensate from varying the proper pressures acting upon the regulator 88. In such event the variable accumulator with its/scale II should be I raised an amount equal to the head represented by the difference. between the curves A and B return pressure the variable accumulator must be raised above the level of liquid m the fixed accumulator an amount vequal to the pressure difierence so that the pressurestat 30 will be maintained in balaricedcondition.

Under this mode ofv operation the radiators ar always filled with steam and the traps I are closed or just sufliciently open to permit the condensate to escape. The traps 'I may here also be dispensed with because the return linepressure is controlled ,to be "asuitable amount below the pressure imposed upon the orifices so that no more steam than enough to flll the radiator will be admitted. v I

I have above described how the system shown in Figure 1 may be regulated by hand according to the mode of operation represented by the constant differential and variable pressure of curves A and B or according to the variable differential and partial filling method of operation represented by the curves C and D.

Now I shall describe the automatic means for effecting the regulation of the system according to either mode of operation.

Automatic thermostat control stats 90, shown in Figure 1', comprises a series of ten running from 20 below zero F; to 70 above zero F. These thermostats are adapted to close their respective circuits when a temperature corresponding substantially to the particular setting of a particular thermostat is attained. That is to say, the thermostat Q is adapted to close its circuit when the outside temperature is substan' tially 70. 3 If the temperature is materially either above or below this point, the circuitthrough the thermostat Q is open. These thermostats are preferably exposed to the outside temperature as on the roof of the building or otherwise exposed to the controlling temperature or to a temperature which is always'substantially proportional to the controlling temperature.

Each of the thermostats has its own circuit" connected to a common return wire on the one side, as shown at 9|, and an individual wire led tor in a corresponding position.

The circuit is relatively simple, as may be seen from Figure 2. The common wire 9| leads to all of the thermostats and their branch wires 95 to I04, inclusive, are connected to contacts in the selector mechanism 93. The selector mechanism has 'a pair of movable b'rushmembers, shown in dotted lines on Figure 2 atl05 and I06. These brush members are adapted to make contact with certain bars I01 and I08 and the aligned contacts which they may overlap. The branch thermostat wires 95 to I04 are connected to con- .tacts 95a to I 03a in the righthand bank in line with the bar I and to the lower contact in the left hand bank which is in line with the bar I0'I. The contacts'96a to I03a are connected in multiple to the contacts 96b to I03b in the left hand, bank of contacts. The two wipers I05 and H16 slide upon rods I09and H0, respectively, and these rods in turn'are connected through brushes Ill and H2 through separate branches containing controlling magnets H3 and H4 to a common wire 5 extending to the operating motor II6 to thesource of current III, which may be any source of commercial current such as a 110 volt A. C. or D. C. circuit.

The ma ts H3 and H4 control the actua-- tion of the two brush members I05 and I06 which are connected together to cause the same to move down or up, respectively. This will be more fully understood by reference to Figures 3 and 4. The

selector mechanism including the contacts and movable brush members is shown more in detail in Figures 6 to '10, inclusive.

Referring now to the construction. shown in Figures 3 to 5 I shall describe the operation of the cam selector mechanism which causes a motion of the brush members to seek a. position corresponding to the-lastenergization of a thermostat circuit. It is to be understood that the corresponding motion is taken from said mechanism and applied to the variable accumulator '10 so as to move it to different positions which will give the necessary heat emission from the radiators to correspond to that required to maintain the room at the predetermined temperature inside when'a specific temperature as determined by the closing of a thermostat circuit prevails on the outside.

C'am selector mechanism v Referringmore particularly to Figures Band 4, I provide a frame "I20 upon which is mounted the driving motor H6 and the mechanism driven thereby. Thisbase plate or frame I20 is preferably supported upon suitable supporting legs .I2I, as showninFigure 1.

The shaft of the motor H6 is connected through a flexible coupling I22 to a propeller shaft I23 which carries at its end a conical friction pulley .I24. This conical friction pulley is adapted to engage with one side or the other of the conical groove I25 in the wheel I26. When the conical pulley'l 24' engages with the lower side m, as shown in Figure 4, the wheel I26 will be driven in one direction, and when the conical pulley I24 engages with the upper conical flange I28 the wheel is driven in the opposite direction. The propeller shaft I23 is supported adjacent the pulley I24 in a movable bearing I29 which comprises a stationary guide member I30, in which a sliding box I3I is guided and this sliding box I 3| has a movable bearing I32 which permits of rocking of the shaft I23 sidewise without bindingisaid bearing I32 upon the shaft I23. The. shiftable box or slide I3I is connected at opposite sides through links such as 133 and I34 to 5 bell crank leversv I35 and I36, the longer arms of which are connected through tension springs I31 and I38 to the cores of solenoids H3 and H4. These solenoids have their windings connected in series with the winding of the motor I I6. Hence:

the energization of the circuit including either one of these solenoid windings also energizes the motor IIB sothat, depending upon which solenoid is energized, the wheel I26 will be drivenin. one direction or the other. While Lhave shown the solenoids I I3 and I I4 in series with the motor, it is to be understood that they may be otherwise arranged so long as the control of the driving motor in a proper direction is exercised by the selector. 9 r t The wheel I26 is mounted on a shaft I39 supported in a suitable journal I40 and it carries, at

its opposite end, the pinion I, which pinion in turn meshes with a large gear wheel I42 bearing a pinion I43 which in turn meshes with the large gear wheel I44 mounted upon the shaft I45 of the winding drum I46, which winding drum is composed of two sections, namely, I41 of large diameter and I48 of small diameter, as illustrated in Figure 5.

The winding drum shaft which is driven by the large gear I44 has a pinion I50 adjustably mounted thereupon as by means of the clamping nut I50. The pinion I5I meshes-witha large gear wheel I52 which has mounted thereupon or connected thereto the cam I53, the gear wheel I52 and cam I53 being adjustably mounted upon the spindle or shaft I54 as by means of the clamping nut I55. The reason for the adjustable clamping of the pinion I50 and gear wheel I52 is to permit of individual adjustment of the winding drum I46 and the cam I53. The shafts of the respective gears and pinions are supported on one side by a downwardly extending plate I56 connected to the top plate of the base I20, and on the other side these shafts are supported by a narrow plate I51 ,next to said side plate I56 as by means of suitable posts or "pillars. The detailed construction of this mechanism may be widely varied, it being remembered that there is to be a'winding drum and a cam jointly operated in one direction or the other by a suitably controlled motor mechanism.

The cam I53 cooperates with a follower or stem I60 which is connected to the brushes of the selector mechanism, as may be seen by reference to Figures 6 and '1. The stem I60 has a follower roller I6I which rides upon the edge ofthe cam.

As shown in Figures 3 and 6, the selector brush mechanism is at substantially the upper limit of its motion and the cam is substantially at the limit of its motion in one direction. The cam selector comprises a plate or mounting board of insulation I63 (see Figures 6 to 10, inclusive) and upon it are mounted the contactsand bars heretofore mentioned and the guide rods I09 and H0 with their respective brushes III and H2 which normally engage therewith but which are adapted to be separated from the guides when the brush member reaches the limit of its motion. The brush member, designated as a whole I65, comprises two separate sets of contact making apparatus which I have designated the brushes I06 and I06, but which in reality consistof a series of contact fingers to insure good contact with.the bars and stationary contacts, respectively. The brush member I65 comprises'a plate or frame I66 having lugs or brackets I61 and I68 at its ends, the lower lug or bracket I68 being connected to the rod I60 so that the two brush members I06 and I06 are moved in unison. Between the lugs or brackets I61 and I68 I mount sets of swinging fingers such as I68 comprising the brush I06 and the swinging fingers I10 comprising the brush member I05. These swinging fingers have hubs which are drilled and mounted either directly upon the rods I09 and H0, or they maybe mounted upon separate sleeves supported by the lugs or brackets I61 and I68 and said sleeves then mounted upon the rods I06 and I I0.

It will be seen that the separate swinging fingers can adjust themselves to any irregularities of the stationary contacts and to permit this to a maximum degree I provide individual springs I1I mounted in individual pockets I12 for each one-of the brush members.

In order to provide a position limit for the motion of the selector brush I65 I provide inclined projections I14 and I15 upon the lugs or brackets I61 and I68, respectively, for lifting the brushes III or I I2, respectively, upon motion of the brush member I65 to the limit of motion in either direction. The operation of the ,cam selector will readily be understood by reference to Figures 2 and 6 to 10. Assume that when the brushes I05 and I06 are in the position shown in Figure 2, namely at the top of the stroke corresponding to minimum heat emission from the radiators due to relatively high outside temperature. If now the outside temperature should drop to 60 so that the thermostat R is closed, the closing of the circuit of the thermostat R energizeswire 96, contact 8641 and contact 66!), which in turn transmit current to the brush III and to the controlling solenoid H3 and motor II6. Thereupon the cone pulley I24 is pressed against the corresponding side of the wheel I26 to cause the cam to be rotated clockwise, as viewed in Figure 3, allowing the selector brush to drop. The selector brush upon leaving the contact 96!) opens the circuit and stops further movement. The sep-.

While I have shown the thermostat as closin for temperatures which are substantially 10 apart, it is to be understood that in practice the steps may be made much smaller, if desired.

The thermostats are so constructed that they will close the circuit within a small temperature range corresponding to substantially a given temperature and open the circuit for a temperature range on either side of the selected temperature.

' The thermostats Individual thermostats are of the construction shown in Figures 22 to 24 in the preferred form of the invention. A suitable channel bar I is provided for a mounting for the thermostats.

The thermostats each comprise a bimetallic spiral element I8I the outer end of which is secured to the bottom of the channel bar I80 as by means of the bolt I82. The inner end of the spiral element I6I is clamped to a post I63 which is preferably square in cross-section. The clamping plate I84, which is held by means-of the screws I86, to the post I88 clamps the inner end of the spiral element to the post-.

The ends of the post I88 are fitted into sockets I86 formed in plates I81,these sockets preferably being formed by securing a washer I88 having a square hole therein to the plate I81. Suitable cradle members I60 and I9I are secured in contact with the'plate's I81 as by means of the screws I88 which extend through the cradle members and the plates I81 and into the posts I83. 'men as I 92 cooperating with graduations on the plates I81 as indicatedat I93 in Figure 22. The cradle members I90 and I9I are preferably formed oi.

sheet metal and they support mercury glass bulb switch elements I94 and I95, these switch elements being so adjusted that at substantially a single critical position the circuits will be closed in series through both of them but upon tilting of the posts I83, that is rocking in either direction irom thecritical position, the circuit will be opened at one of the contacts or the other. Thus my system operates on normally open circuits, but it is apparent to those skilled in the art that the reverse operation might be true, namely, that the system might operate on normally closed circuits and that the opening of the circuit by thermostatic movements of the switch members to a predetermined position might control the movement. The two mercury bulbs I94 and I95 are connected in series and so adjusted that for substantially a given temperature value the circuit is closed through both of them simultaneously but upon change of temperature the post I83 will be rocked to open the circuit for either a higher or a lower temperature.

I do not intend to limit the system to the use of this specific form of thermostat, as any equivalent mechanism for selecting a particular circuit in response to the prevalence of a certain outside temperature or temperature range may ployed. For instance, in Figure 26 I have shown a thermostat with a single active element. In this case a bar I91 preferably of a material which has a minimum thermal coefllcient of expansion supports a member such as the wire I99 in tension between the fixed abutment 200 on the member I91 and a swinging arm 20I pivoted at 202 on the frame member I91 and maintained in tension by the weight 203 acting upon the arm 204. a A longer arm 205 giving greatly multiplied motion carries a brushmember 206 cooperating with the contacts of,-a contact bank 201 containing contacts which are closely grouped and adapted to be selected by said brush 206 in accordance with the contraction and expansion of the wire or tape I99. In this manner a particular circuit is closed for substantially a particular outside tempera/ture The contact 206 may be caused to jump from one contact of the bank 201 to the next "one by interposing ridges of insulation which cause the contact or brush to hop with a definite snap motion from one contact to the other.

Winding drum The winding drum I48 has a suitable cable 209 connected thereto, this cable being extended over pulleys such as 2I0 and 2H and connected to the variable accumulator I0 as by means oia lug formed on to of the chamber 66. a

Assume that the cable ishonnected to the larger portion I4I of the drum, that is the portion which is of the larger diameter, it will be seen that a greater range. of motion will be caused than if the cable were wound solely upon the smaller diameter portion I48.

The relation of the cam I53'to the drum I48 is important as by this relation the various pressures of steam in the supply main 2 are controlled by the various steps of the thermostat bank 90. The steps of the thermostat bank 90 are. shown as being of equal values, that is-equ'al increment or decrement of, for example, 10. Assume that the predetermined room temperature is 70. It will be apparent, oi course,that heatemis'sion be emsions of-heat from the radiators in accordance with outside requirements through the working 9 from the radiator is a function of temperature diiference inside and outside, assuming always that the same amount of surface is active or that the character of medium upon each side of the radiator is the same. 6

Where the control orifices 6 govern the rate or heating fluid admission to they radiator for partial filling, it is to be remembered that the rate of fiow through the orifice is within limits substantially in accordance with the well known formula of V =2gh, where V is velocity, 9 is acceleration due to gravity and h is the pressure difference or head. In order, therefore, to secure equal increments in flow it is necessary that the pressure difference be varied in accordance with the square root law. It will be apparent, therefore, that the cam I53 in such a system should be generated according to that law throughout so much of the range of the system as corresponds to operation according to partially 20 filled radiators. If the system works throughout its range on the partial filling, then the cam as a whole is generated on increments of throw which are in accordance with t e square roots of increments of revolution.

The cam is a real controlling element since it 'perates the brush mem'ber I65 to bring the same to the selected position as determined. by

the energized thermostat circuit, and it may, therefore, be considered that the increments of throw are uniform and that the increments of rotation are variable. This gives variable increments of lift or drop of the variable pressure accumulator I0. In Figure 13 I have indicated a spiral or snail 85 shell cam in which the square root law is ,embodied particularly between the points 25 and 10. Between the successive positions marked according to temperature readings the outward throw is the same but the angular motion is different in 0 accordance with the curve A-EC of Figure 25. While the cam shown in Figure 13 embodies two revolutions it is obvious that any number of revolutions desired may be employed, the cam follower being changed in proportion and the winding drum being also suitably proportioned. i The cam shown in Figure 13 is generated to control in accordance with the scheme of partial filling as illustrated by curves C-D on Figure 25, but obviously the cam maybe generated to provide ,the respective pressures indicated on the curve A. That is to say, by using a differential,

- controlling regulator the curve B is maintained always at a predetermined value below the curve A; the saidpoints on curve A may be maintained by variations of positions of the variable accumulator I0 and this in turn is controlled by the cam. It will thus be seen that my system is capable or automatically controlling the emisrange of the system'and according to either system of steam supply, that is either constant differential and variable temperature and pressure or at variable supply pressure constant return pressure and partial filling otthe radiators.

Now I shall describe in connection with Figure 27 the preferred embodiment of the invention which is based on the regulation of heat emission from the system partially by variable filling of the radiators for lower heat requirements and partially by complete filling of the radiators with variable pressure steam for the higher heat requirements. In other words for milder outside 7 to the other where the period or point of transitemperature the variable differentiates between supply and return as represented by the part of tinuous curve of supply pressure the curve C-D to the right of the point E-F are employed and for colder temperatures con- By reference to Figure it may be seen that the increments of pressure from 25 to 70 are very small whereas the increments of pressure from 25 to zero are very large. If the cam and .drum be related for the small steps of pressure,

the small part of the winding drum should be employed and where the larger stepsof pressure are to be employed the larger part of the drum 0 could advantageously be employed. Now in the dual system of my invention where the heat emission is controlled in part of the range by variable volume and in the, remainder of the range by variable temperature the cable 209 is preferably passed from one part of the drum tion occurs.

Itwill be understood also that where this period of transition or change from the one theory to the other occurs that the return line pressure should be differently controlled. This may readily be done by switching the constant pressure regulator into control of the motor 9 for .the

vacuum pump l0 for the range to the right of points EF on the curve of Figure 25 andswitchingin the constant differential regulator 83 for that part of the range lying to the left of points E-F in Figure 25. .This may be done by a simple selector switch 88 controlled by the cam selector in passingthe points EF as by a simple.

commutator switch or the like as shown in Fig. 1.

I may, however, as shown in Figure 27, employ a special control member in the form of a sepa-- rate variable pressure accumulator 220 which is like the pressure accumulator I0 that controls the steam pressure. It cooperates with a fixed pressure accumulator 22l and a pressurestat 222' to control the vacuum maintained in the return line 3. The large diameter portion of the drum I43 has an additional cable 223 extending over pulleys 224 and 225 and connected to th variable accumulator 220. The winding cable 223 plays only over the larger diameter part of the drum I whereas the cable 209 which operates the variable accumulator I0 plays partly on the larger diameter part I" and'partly on the smaller diameter part I49, the point of transition being the point E on the curve shown in Figure 25. If desired, the cable 223 may be merely branched from the cable 209 and it then goes slack when the head 220 rests upon the base 229.

Thus so long as the cable 209 is playing on the larger diameter portion of the drum I43 the two accumulator heads 66 and 228 will rise and fall together. It is to be observed that for the maximum heat requirement position which is shown inFigure 27 the heads 60 and 226 are at the upper end of their travel. The head 06 is maintained a predetermined distance above the head 220. This head represents the constant differcontacts to cause the appropriate motor to drive shown in Figure 27 which corresponds to the 10' to the right of the point F m Figure 25. When the head 22s rests in the socket 228 the head 06 of the variable accumulator i0 is still free to 10 -move. Such arrival of the. head 228 upon its rest 229 corresponds with the arrival of the head 56 in a position corresponding'to the point E and corresponds also to the change of the cable 209 from the large diameter portion to the small 15 diameter portion. Thereafter for rotation of the drum I43 in lowering the head 66 smaller increments of motion corresponding to the smaller increments of pressure occur due to the changed relation-of the diameter of the drum to the rota- '20 tions of the'cam I53. When the cable 209- is r1m ning on the small diameter portion I48 a predetermined angular motion of the shaft of the drum results in proportionally less motion of the head 63. 25

The pressurestat 30 may be of the construction shown in Figure 1 and likewise the construction of the pressurestat 222 may be as shown at 30 in Figure 1, the pressurestat 30 controlling the switch for the motors H and I2 to open 30 and close the control valve 2 and the pressurestat 222 controlling a switch 229 which governs the motor 230 of the vacuum pump l0. The operatlon of the thermostats and the selector switch 93 is as described in Figure 1 and it is 35 coordinated through the cam I53 with the winding drum I46, as previously described. Instead of employing a single'motor and a clutch-for, determining the direction of rotation of the drum and cam, have shown two motors connected to the same worm shaft 233, the two motors 23l and 232 being included in di erent branches and governed by the brushes I05 and I03 cooperating with the stationary bars and the drum and the cam until the cam sliifts the brushes I05 and I03 to the proper position as determined by the thermostats inthe bank 90.

The reason for the two diameter drums will more readily apparent from a consideration of the diagram shown in Figure 28, which shows the character of the curve obtainable by the system shown in Figure 27. Instead of a smooth curve KB the step curve a-b is obtained. Likewise, instead of the smooth curve C. the step curve 0' is obtained, the uniform, return line pressure curve d being the same since that remains constant and is not stepped.

Now by laying Figure 28 alongside of Figure 27, part 2, and considering the figures of absolute pressure applied to the ordinates at the left of Figure 28 and ,also at the left of Figure Operation of the dual system Assume that the parts are in the position upper left hand part .of the curve of Figure 28. The level in the chamber 66 stands above the 7 level in the chamber by a predetermined amount, and it may be assumed that atmospheric pressure prevails over both the level .in 08 and in 51. The level in the chamber 223 stands even with the level of liquid in the cham- 15 

